<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* .test1 section {
            margin-bottom: -9999px;
            padding-bottom: 9999px;
        } */

        .test4 {
            height: 500px;
            display: flex;
            justify-content: space-between;
            border: 5px solid yellowgreen;
        }

        .test4 div {
            flex: 1;
            background-color: aqua;
            border: 5px dotted ghostwhite;
        }
    </style>
</head>

<body>
    <!-- <div class="test1">
        <section>左边的列高</section>
        <section></section>
    </div> -->
    <!-- <div style="border-left: 100px solid #F60;">
        <section style="margin-left: -100px;">左边的列高</section>
        <section></section>
    </div> -->
    <!-- <div style="background: url('https://images.pexels.com/photos/4946814/pexels-photo-4946814.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260') repeat-y;">
        <div>左边的列高</div>
        <div>右边的列高</div>
    </div> -->
    <div class="test4">
        <div>左边</div>
        <div>右边</div>
    </div>
</body>

</html>